Higher Head Rice Yield Research Articles

Analysis of Erect-Panicle Japonica Rice in Northern China: Yield, Quality Status, and Quality Improvement Directions.

China is the only country that extensively cultivates the indica and japonica rice varieties, with the largest japonica rice production area being in northeast China. A study of the relationship between the yield and quality of japonica rice and the effect of nitrogen fertilizer application on this relationship is important. In this paper, we aimed to assess the current yield and quality of japonica rice in northeast China. We selected erect-panicle varieties as the test materials. Field experiments were conducted using different nitrogen fertilizer levels for two consecutive years to analyze the rice varieties' yield, quality, interrelationship, and nitrogen fertilizer response. The average yield following high- and low-nitrogen treatments exceeded 10,000.00 kg/hm2, with a maximum of 12,285.63 kg/hm2. The high-yield-high-nitrogen treatment group had more panicles, a higher seed-setting rate, and a higher 1000-grain weight than the other groups. The high-yield-low-nitrogen group had a higher number of panicles and seed-setting rate than the other groups. The low-yield-high-nitrogen group had a lower number of whole grains, grain length-to-width ratio, and taste value than the other groups. The low-yield-low-nitrogen group had fewer primary branches than the other groups; excluding the primary branch-setting rate and 1000-grain weight, the values of the other panicle traits of the group were significantly higher than those of the other groups. The high-nitrogen-high-flavor group had lower panicle and spikelet numbers and higher spikelet fertility rates than the other groups. The low-nitrogen-high-flavor group had higher spikelet fertility rates and 1000-grain weight than the other groups. Compared to the other groups, the low-nitrogen-high-flavor group had a higher head rice yield, and the high-nitrogen-high-flavor group had a lower chalkiness rate. The main goal of the breeding and cultivation of high-yield and high-quality erect-panicle japonica rice in northern China is to achieve "dual high, dual low, and one high and one low" conditions, signifying a high yield with high or low nitrogen levels, low protein and amylose contents, high head rice rates, and low chalkiness. This study provides a new technique for enhancing the taste of northern erect-panicle japonica rice to promote the sustainable, high-yield, and high-quality development of japonica rice in northern China.

Mild Hydrothermal Treatment for Improving Outturn of Basmati Rice

Hydrothermal treatment of rice, called “Parboiling”, is an ancient traditional process in Asian countries. It consists of soaking rough rice in water and steaming it, and it both reduces the level of grain breakage and increases head yield of rice during milling. However, parboiling of rice is associated with some drawbacks regarding consumer preferences: the loss of its aroma, reduced rice-kernel whiteness and increased kernel hardness. This research study was carried out to develop a mild hydrothermal treatment that could be applied to basmati paddy by controlling hydrothermal treatment, i.e., soaking water temperature, steaming pressure and time. The Basmati 370 paddy variety was used for this study. The results revealed that, by soaking the paddy in hot water (70 ± 2 °C) for 75 min and steaming the soaked paddy for 20 min with non-pressurized steam at atmospheric pressure, and soaking the paddy for 120 min in hot water (70 ± 2 °C) and steaming the soaked paddy for 4 min with pressurized steam (4 kg/cm2), the optimum treatments are achieved. These optimum hydrothermal treatments were able to produce high head rice yield and preserve the basmati aroma, colour, hardness and palatability characteristics similar to non-parboiled basmati rice. Further, nutritional values such as vitamin B and protein content were also significantly preserved by these mild hydrothermal treatments. These optimized treatment combinations achieved minimized grain breakage while increasing head rice yield during milling and, at the same time, preserved basmati aroma, kernel whiteness, cooking and palatability characteristics similar to non-parboiled rice.

Regulation of 2-acetyl-1-pyrroline and grain quality in early-season indica fragrant rice by nitrogen and silicon fertilization under different plantation methods

Fragrant rice has a high market value, and it is a popular rice type among consumers owing to its pleasant flavor. Plantation methods, nitrogen (N) fertilizers, and silicon (Si) fertilizers can affect the grain yield and fragrance of fragrant rice. However, the core commercial rice production attributes, namely the head rice yield (HRY) and 2-acetyl-1-pyrroline (2-AP) content of fragrant rice, under various nitrogen and silicon (N-Si) fertilization levels and different plantation methods remain unknown. The field experiment in this study was performed in the early seasons of 2018 and 2019 with two popular indica fragrant rice cultivars (Yuxiangyouzhan and Xiangyaxiangzhan). They were grown under six N-Si fertilization treatments (combinations of two levels of Si fertilizer, 0 kg Si ha−1 (Si0) and 150 kg Si ha−1 (Si1), and three levels of N fertilizer, 0 kg N ha−1 (N0), 150 kg N ha−1 (N1), and 220 kg N ha−1 (N2)) and three plantation methods (artificial transplanting (AT), mechanical transplanting (MT), and mechanical direct-seeding (MD)). The results showed that the N-Si fertilization treatments and all the plantation methods significantly affected the HRY and 2-AP content and related parameters of the two different fragrant rice cultivars. Compared with the Si0N0 treatment, the N-Si fertilization treatments resulted in higher HRY and 2-AP contents. The rates of brown rice, milled rice, head rice, and chalky rice of the fragrant rice also improved with the N-Si fertilization treatments. The N-Si fertilization treatments increased the activities of N metabolism enzymes and the accumulation of N and Si in various parts of the fragrant rice, and affected their antioxidant response parameters. The key parameters for the HRY and 2-AP content were assessed by redundancy analysis. Furthermore, the structural equation model revealed that the Si and N accumulation levels indirectly affected the HRY by affecting the N metabolism enzyme activity, N use efficiency, and grain quality of fragrant rice. Moreover, high N and Si accumulation directly promoted the 2-AP content or affected the antioxidant response parameters and indirectly regulated 2-AP synthesis. The interactions of the MT method with the N-Si fertilization treatments varied in the fragrant rice cultivars in terms of the HRY and 2-AP content, whereas the MD method was beneficial to the 2-AP content in both fragrant rice cultivars under the N-Si fertilization treatments.

The effect of rice milling time and feed rate on head rice yield and color properties

This study has been carried out to evaluate the head rice yield, kernel broken and the chance of color depend on milling time and feed rate. In this study, threshed rice kernels by combine-harvester at different cylinder speeds, rice harvesting season in 2018, were used for experiment test. According to results, head rice yield decreased slightly as the cylinder speed increased, with yields varying between 71.40 % and 70.28 %. Processing time was found to have a highly significant effect (p<0.01) on the quantities of unbroken kernel, broken kernel, bran, yield and husk. The highest rate of broken kernel was obtained at a processing time of 25 seconds, and the lowest values were obtained at a processing time of 10 seconds. With a processing time of 10 seconds, the quantities of unbroken kernel, broken kernel, bran, yield and husk were 70.74, 3.260, 0.810, 74.37 and 24.82 %, respectively. When the processing time was 25 seconds, the quantity of broken kernel decreased from 70.74 percent to 62.86 percent, and yield decreased from 74.37 % to 67.58 %. The broken kernel ratio increased from 3.26 percent to 4.633 percent and bran ratio increased from 0.8642 percent to 1.822 percent. Husk ratio, on the other hand, increased from 24.82 % to 30.60 %. In other words, as the processing time increased, so did the bran ratio and husk ratio. The highest whiteness value of 70.92 was obtained at a processing time of 25 seconds; while the lowest whiteness value of 63.81 was obtained at a processing time of 10 seconds. There were declines in a and b values as processing time increased, although the differences were not statistically significant. The highest a and b values were obtained at a processing time of 10 seconds, with -0.690 and 15.01, respectively. In conclusion, when processing paddy to rice, processing time needs to be increased to obtain a whiter rice; to have fewer broken kernels and a higher head rice yield, on the other hand, the processing time needs to be short.

Deep placement of liquid fertilizer at tillering stage influences grain quality, 2-acetyl-1-pyrroline synthesis, and antioxidant response of fragrant rice

In recent years, the deep placement of solid fertilizers has become popular in rice production due to high fertilizer utilization efficiency and productivity. There is limited knowledge about the effect of deep placement of liquid fertilizer at the tillering stage on grain quality and productivity of fragrant rice. Therefore, a two-year field experiment was conducted from 2019 to 2020 with two fragrant rice cultivars Yuxiangyouzhan (YXYZ) and Xiangyaxiangzhan (XYXZ) under four fertilization treatments: no fertilizer application (T1); application of solid fertilizer (150 kg ha −1 NPK; broadcasted 90 kg ha −1 NPK as basal fertilizer and 60 kg ha −1 NPK at the tillering stage, T2); application of liquid fertilizer with 10 % less N (broadcasted 90 kg ha −1 NPK as basal fertilizer and deeply placed 45 kg ha −1 N and 90 kg ha −1 PK at the tillering stage, T3); application of liquid fertilizer with 20 % less N (broadcasted 90 kg ha −1 NPK as basal fertilizer and deeply placed 30 kg ha −1 N and 90 kg ha −1 PK at the tillering stage, T4). The study showed the highest 2-acetyl-1-pyrroline (2AP) content under T3 treatment (2019, 115.35–120.11 μg kg −1 and 112.97–130.30 μg kg −1 , 2020). The proline (PRO) content, proline dehydrogenase (PDH) activity, 1-pyrrolin-5-carboxylic acid (P5C) content, and 1-pyrrolin-5-carboxylic acid synthase (P5CS) activity also improved under T3 and T4 treatments compared with T2 treatment. Besides, the T3 and T4 treatments increased the protein content and decreased the chalkiness degree and chalky rice rate compared with the T2 treatment. Moreover, T3 and T4 treatments improved the superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) activities and reduced the malondialdehyde (MDA) content of the leaves compared with the T2 treatment. Further, the structural equation model revealed that POD and CAT and rice appearance quality had significant positive effects on 2AP content, and that POD and CAT indirectly affected 2AP content by showing a significant positive effect on the PRO. The T3 treatment also showed relatively stable and higher head rice yield and net income in the two-year field experiment. Overall, side deep placement of liquid fertilizer improved the 2AP synthesis, and antioxidant response of fragrant rice and under T3 treatment, the head rice yield was stable and the economic income was higher. Therefore, in the future of agricultural production, it is recommended that farmers use liquid fertilizer with 10 % less N (T3) to improve the quality and stress resistance of fragrant rice and obtain stable and more economic benefits. • Deep placement of liquid fertilizer at tillering stage improved 2-acetyl-1-pyrroline and grain quality of fragrant rice. • Deep placement of liquid fertilizer at tillering stage enhanced antioxidant enzyme activities in leaves of fragrant rice. • The relationship among antioxidant response, 2-acetyl-1-pyrroline, and grain quality in fragrant rice were interpreted. • Optimization of deep placement of liquid fertilizer at the tillering stage yield higher economic income.

Evaluating the Processing Parameter of Milling, Cooking and Thermal Properties on Selected Varieties of Rice in Ebonyi State, Nigeria

Nigeria farmers are rice producers growing many varieties and prone to accepting any new varieties with seemingly better grain yield and qualities. This study analyzed the quality aspects of milling, cooking and thermal properties of selected rice varieties. Ten paddy rice varieties were processed to raw rice and analyzed for their milling, cooking and thermal properties. The results shows that IWA 7 had the highest head rice yield and least broken grain while IWA 8 had the least head rice yield and highest broken grain. Agreement and Argwula had the highest total milling yield while IWA 1 had the least. IWA 2 had the highest brown rice while Argwula had no brown rice. There were no unmilled grains and stones were found only in Argwula and IWA 3 varieties. Faro 52 had the highest immature and no chalky grain. The gelatinization temperatures were intermediate. Agreement had the highest percentage of amylose content while Faro 44 had the lowest. The volume expansion ranged from 1.5 to 7. The thermal conductivity values ranged from 0.332 to 0.354 WmoC, the specific heat capacity values ranged from 3.44-3.89 kJ/kg oC and thermal diffusivity ranged from 0.75 to 0.80m2/s. Varieties with higher amylose content required a shorter cooking time. This makes IWA 6 and Agreement the varieties with the best cooking quality. Thermal properties were good for all the varieties and the rice grains exhibit the ability to retain heat better than other existing varieties. Keywords: Rice Varieties: Amylose: Parboiling: Specific Heat Capacity: Rice Grain Quality

EFFECT OF TWO STAGE DRYING EMPLOYING FLUIDIZED BED DRYING, TEMPERING FOLLOWED BY FIXED BED DRYING ON HEAD RICE YIELD OF BRRI DHAN28 RICE VARIETY IN BANGLADESH

Drying of high moisture paddy to achieve quality milled rice is an important issue in a paddy producing country like Bangladesh. This study has been conducted to investigate the impact of two stage drying technique namely, fluidized bed drying, tempering and followed by fixed bed drying method on quality of BRRI Dhan28 rice variety in terms of head rice yield (HRY). Moist paddy was dried in fluidized bed dryer (FBD) as first stage drying to reduce moisture from 25-27% to 18-19% using three drying temperatures of 120, 130, and 150°C at three bed thicknesses of 8, 10, and 12 cm. The first stage dried samples were immediately tempered for 30 minutes and dried in second stage drying by fixed bed dryer using 40±10C temperature maintaining bed thickness as 30 cm for the further reduction of moisture content to 13-14% (wb). Sun drying method was followed as complete drying of control sample. Control sample was used to compare the milling quality of rice dried in two stage drying technique. In addition, head rice yield was also compared to existing industrial paddy drying complexes. The results revealed that HRY of rice samples obtained from different drying methods was comparable. All the sets of drying parameters in two stage drying yielded better quality HRY than the control and even existing industrial drying method. The highest HRY (53.43%) of milled rice was obtained in the two-stage drying. On the other hand, the samples dried in the sun drying and industrial drying using Louisiana State University (LSU) dryer yielded 49.77% and 48.25% HRY, respectively. Therefore, the two-stage drying technique can be used for drying of high moisture paddy to obtain quality dried rice.

Rice ADT 51 - A high yielding long duration rice variety suitable for Samba season in Cauvery Delta Zone of Tamil Nadu

In Tamil Nadu, rice is the predominant crop during samba season. In the Cauvery Delta Zone around 2.5 lakh hectares purely depend on water from Cauvery in Samba season during the normal years of water release from Cauvery, CR 1009 is predominantly grown variety without any alternate varieties. Mono cropping of CR 1009 leads to susceptibility to pests such as brown plant hoppers (BPH) stem borers and diseases such as blast, bacterial leaf blight (BLB), grain discolouration and false smut. In order to provide a choice variety to farmers’ one long duration rice culture, AD 09367 a derivative of the cross BPT 5204 / Improved White ponni was released as Rice ADT 51 during the year 2018. ADT 51 matures in 155 to 160 days with tall, erect and high tillering plant habit and well adapted to single season canal dependent rice growing areas of Cauvery delta for Samba season (August-September sowing). ADT 51 has recorded a mean grain yield of 6533 kg/ha which is 9.8 and 12.7 per cent higher than CR 1009 (5947 kg/ha) and ADT 50 (5796 kg/ha) respectively. At Thiruvisanallur, Thanjavur district it manifested highest yield of 10036 kg/ha and the OFT farmer, Mr. Baskar received first prize in the district level crop yield competition for the year 2016. Besides its yield superiority, ADT 51 is resistant to blast and moderately resistant to leaf folder, stem borer, BPH, Sheath blight and sheath rot. The milled rice of this variety is white, medium grade with a 1000 grain weight of 23.9 g. High milling and head rice yield and cooking qualities of ADT 51 are comparable with CR 1009. Opinion from farmers revealed that, vigorous growing nature and tolerance to major pest and diseases of this culture requires less inputs especially nitrogenous fertilizer and plant protection chemicals for cultivation. The characters such as more no. of productive tillers, less chaffiness and quick establishment of seedling are its added advantages.

Parboiled Paddy Drying with Different Dryers: Thermodynamic and Quality Properties, Mathematical Modeling Using ANNs Assessment.

The effect of hybrid infrared-convective (IRC), microwave (MIC) and infrared-convective-microwave (IRCM) drying methods on thermodynamic (drying kinetics, effective moisture diffusivity coefficient (Deff), specific energy consumption (SEC)) and quality (head rice yield (HRY), color value and lightness) characteristics of parboiled rice samples were investigated in this study. Experimental data were fitted into empirical drying models to explain moisture ratio (MR) variations during drying. The Artificial Neural Network (ANN) method was applied to predict MR. The IRCM method provided shorter drying time (reduce percentage = 71%) than IRC (41%) and microwave (69%) methods. The Deff of MIC drying (6.85 × 10−11–4.32 × 10−10 m2/s) was found to be more than the observed in IRC (1.32 × 10−10–1.87 × 10−10 m2/s) and IRCM methods (1.58 × 10−11–2.31 × 10−11 m2/s). SEC decreased during drying. Microwave drying had the lowest SEC (0.457 MJ/kg) compared to other drying methods (with mean 28 MJ/kg). Aghbashlo’s model was found to be the best for MR prediction. According to the ANN results, the highest determination coefficient (R2) values for MR prediction in IRC, IRCM and MIC drying methods were 0.9993, 0.9995 and 0.9990, respectively. The HRY (from 60.2 to 74.07%) and the color value (from 18.08 to 19.63) increased with the drying process severity, thereby decreasing the lightness (from 57.74 to 62.17). The results of this research can be recommended for the selection of the best dryer for parboiled paddy. Best drying conditions in the study is related to the lowest dryer SEC and sample color value and the highest HRY and sample lightness.

Modified Steaming Method for Parboiled Rice Production

A modified steaming method (steam using the revolved sieve; SRS) was applied to produce parboiled rice and the qualities of parboiled rice, namely, thermal properties (enthalpy; ΔH and degree of starch gelatinization: DG), head rice yield (HRY) and whiteness index (WI) were investigated under various steaming times and temperatures. The experimental results indicated that time and temperature during steaming step affected the parboiled rice qualities significantly. Prolonged time and increase of temperature during steaming provided the higher initial moisture content and grain temperature of rice sample after steaming, leading to longer time in drying process for decreasing the moisture content in the rice sample to 22% (d.b.). This provided the decrease of ΔH, leading to increase in the DG and resulting in the higher HRY and lower WI values.

Responses of Milling Quality to Nitrogen and Water Management in Modern Long Grain Rice Varieties

This study determined how nitrogen (N) fertilizer and water management affect grain yield and milling quality of 9 modern rice varieties with long, slender grain in two field experiments. The effect of N on rice grown in wetland culture was evaluated at 0, 60 and 120 kg N ha-1. In a second experiment the rice in aerobic and wetland culture were compared. The rice in both experiments were grown to maturity and evaluated for yield, head rice yield and chalkiness. Grain yield increased with increasing N application, head rice yield increased with increasing N in 8 varieties, while chalkiness was more than halved in 7 varieties. Grain N also increased with increasing N fertilizer, but high head rice yield in several varieties was associated with relatively low grain N. Under aerobic cultivation, all 9 varieties yielded less than in wetland culture, the head rice yield was lower and chalkiness was higher except in 2 varieties. In both experiments, grain yield was associated positively with head rice yield and negatively with chalkiness. Head rice yield and chalkiness were negatively associated in the water experiment but not in the N experiment. This study has shown that modern high yielding rice varieties generally respond positively to nitrogen fertilizer in better milling quality as well as in yield. Grain chalkiness of the varieties was more stable against variation in the environment than head rice yield.

Performance evaluation of small scale energy efficient mixed flow dryer for drying of high moisture paddy

Suitable drying technique and energy efficient dryer are important concerns for drying of high moisture paddy. In this study, a small scale mixed flow dryer (MFD), with presenting systematic design approach, was developed and tested for paddy drying. Performance evaluation of the developed dryer in terms of specific energy consumption, instantaneous drying and energy efficiencies, and quality of the milled rice were investigated. A comparative performance analysis between the developed MFD and industrial Louisiana State University (LSU) dryer, which is widely used for paddy drying in Bangladesh, was also studied. In addition, drying kinetics for high moisture paddy was evaluated thorough analyzing outlet air relative humidity. Energy analysis revealed that specific electrical (in terms of primary energy) and thermal energy consumption were 0.97 and 3.17 MJ kg−1 water removed, respectively in reducing paddy moisture content (mc) from initial 25 to 12%, the final mc wet basis. Calculation indicated that 33.1% specific electrical and 21% specific thermal energy consumption can be saved by MFD in contrast to the industrial LSU dryer. The energy and drying efficiency values were found to be varied from 0.85 to 0.90 and from 0.10 to 0.17, respectively. Statistical analysis revealed that paddy samples dried by the MFD yielded 16.01% higher head rice yield than sun drying method. The energy analysis tactics presented in this paper can readily be applied in performance evaluation for heated air drying of different products.

Fissured grain and head rice yield of crops harvested manually or by combine at different ripening stages in Cambodia

ABSTRACTCombine has been well adopted by smallholders in lowlands of Cambodia and is contributing to the development of mechanized rice production for commercial purposes. Broken rice is a major issue for the commercial rice product, and fissured grain at harvest leads to broken rice and lowers head rice yield (HRY) during milling. Factors that determine grain fissures and broken rice were obtained from three studies: an on-farm study of fissured grain, a research station experiment of fissured grain and broken rice harvested at different ripening stages and a mill study of fissured and broken rice during drying and milling processes in Cambodia. There was significant variation in fissured rice percentage among 20 farms sampled, and the fissured grain was negatively correlated with grain moisture content at harvest. Time of harvesting was crucial, as delay in harvesting after 25 days after flowering (DAF) often resulted in lower grain moisture content and higher fissured grain, which subsequently reduced HRY. However, the optimum time of harvesting varied across four seasons for crops harvested manually or by combine. In some years, crops harvested at 35 DAF had rather low per cent fissured grain with subsequently high HRY, this may have been associated with slightly lower temperatures. The mill study showed that fissured grain developed during the drying, storage and milling processes. It is concluded that while grain moisture content at the time of harvest may be used as an indication of subsequent HRY, the latter was more strongly related to fissured grain at harvest.

Improving Head Rice Yield and Milling Quality: State-of-the-Art and Future Prospects.

Increasing paddy yield in rice does not directly translate to enhancing food security because significant decrease in grain yield can happen during postharvest processing of the rice paddy. In parallel with enhancing paddy yield, improving the milling quality of rice is essential in ensuring food security by mitigating the impact of significant losses during the postharvest processing of rice grains. From an industrial standpoint, maximizing the milling recovery of whole grain polished rice is crucial in fetching higher revenues to rice farmers. Significant advances in rice postharvest processing technology have been achieved which are geared toward reducing the incidence of fissures and chalkiness to increase head rice yield (HRY) in rice. The genetic bases of kernel development and grain dimension are also characterized. In addition to these advancements, an integrated phenotyping suite to simultaneously characterize phenotypes related to milling quality will help in screening for breeding lines with high HRY. Toward this goal, modern imaging tools and computer algorithms are currently being developed for high-throughput characterization of rice milling quality. With the availability of more sophisticated, affordable, automated, and nondestructive phenotyping methods of milling quality, it is envisioned that significant improvement in HRY will be made possible to ensure rice food security in the future.

Variations in agronomic and grain quality traits of rice grown under irrigated lowland conditions in West Africa.

Rice breeding in West Africa has been largely skewed toward yield enhancement and stress tolerance. This has led to the variable grain quality of locally produced rice in the region. This study sought to assess variations in the agronomic and grain quality traits of some rice varieties grown in this region, with a view to identifying sources of high grain yield and quality that could serve as potential donors in their breeding programs. Forty‐five varieties were grown under irrigated conditions in Benin and Senegal with two trials in each country. There were wide variations in agronomic and grain quality traits among the varieties across the trials. Cluster analysis using paddy yield, head rice yield, and chalkiness revealed that 68% of the total variation could be explained by five varietal groupings. One group comprising seven varieties (Afrihikari, BG90‐2, IR64, Sahel 108, WAT311‐WAS‐B‐B‐23‐7‐1, WAT339‐TGR‐5‐2, and WITA 10) had high head rice yield and low chalkiness. Of the varieties in this group, Sahel 108 had the highest paddy yield in three of the four trials. IR64 and Afrihikari had intermediate and low amylose content, respectively, with the rest being high‐amylose varieties. Another group of varieties consisting of B6144F‐MR‐6‐0‐0, C74, IR31851‐96‐2‐3‐2‐1, ITA222, Jaya, Sahel 305, WITA 1, and WITA 2 had high paddy yield but poor head rice yield and chalkiness. The use of materials from these two groups of varieties could accelerate breeding for high yielding rice varieties with better grain quality for local production in West Africa.

Effect of Varying Parboiling Conditions on Head Rice Yield for Common Paddy Varieties in Iran

Abstract Various conditions of a parboiling process affect the qualitative parameters of paddy milling. In this study, the effects of drying temperature (45 and 60 °C), moisture content (8, 10 and 12% w.b.), steaming time (10, 20 and 30 min) and paddy varieties (Hashemi and Alikazemi) were investigated on head rice yield (HRY). The samples were husked using a rubber roller husker and whitened by a laboratory abrasive whitener. Results showed that the main effects of all parameters were significant on HRY (P <0.01). The utilization of higher temperature (60 °C), in comparison with non-parboiled rice, without reducing the milling quality was found as one of the advantages of parboiling. Among all experiments, the highest HRY (68.647%) was achieved in the combination of Alikazemi/45 °C/10 min/8%. In the majority of cases, the combinations including Alikazemi variety had higher HRY than Hashemi. For Hashemi variety, the highest HRY (67.297%) was achieved in combination 45 °C/10 min/8%. In terms of HRY, parboiling causes an increase of 25.8% and 43.3% respectively for Hashemi and Alikazemi. Therefore, it is highly recommended in processing of Alikazemi variety.

HEAD RICE YIELD OF CROPS HARVESTED BY COMBINE AND HAND AT DIFFERENT RIPENING TIMES IN CAMBODIA

SUMMARYExperiments were conducted across 2 years to determine the effect of harvesting methods – combine harvester and hand harvesting – and harvest time during ripening on milling quality of long grain rice grown in the rainfed lowland ecosystem in Cambodia. Head rice yield (HRY) was highest when rice was harvested 25 days after flowering and decreased with delay in harvesting at 35 and 45 days after flowering. This was accompanied by a general decline in grain moisture content at harvest, although it was still high at 24–25% at 35 days after flowering. The decline in HRY was associated with increases in fissured grain percentage observed immediately after harvest. Hand harvesting produced 2–6% higher HRY than combine harvesting. Fissured grain in hand harvested crops was lower in year 1, but was similar to combine harvested crops in year 2. Both hand and combine harvested crops were sun-dried but rough rice harvested by combine was dried on plastic sheet and this may have contributed to reduction in HRY. Maximum HRY percentage was only about 44% and the factors contributing to this low HRY were discussed. Harvesting time and methods had no significant effect on grain yield, but the field grain loss during the harvesting operation was 2–5% higher in combine than hand harvesting.

Rice grain protein composition influences head rice yield

Background and objectivesThe objective of this study was to determine the extent to which differences in rice grain protein composition are associated with head rice yield (HRY). HRY, the mass of milled unbroken rice grain derived from a defined mass of paddy rice expressed as a percentage, is a commercially important trait targeted by rice breeders. Variation in rice grain protein composition influences rice grain texture, and high grain protein content is associated with high HRY; however, the relationship between rice grain protein composition and HRY is not well understood.FindingsHPLC analysis of protein extracts derived from broken and unbroken milled medium‐ and long‐grain rice suggests that rice grain protein composition differences are associated with HRY. Glutelin, a major class of rice grain storage proteins, displayed the greatest difference between broken and unbroken rice grains but weakest association with HRY. Prolamin and globulin content displayed relatively smaller differences between broken and unbroken medium and long grains, yet both protein fractions were associated with HRY.ConclusionsRice grain protein composition, in addition to other known factors, influences rice HRY.Significance and noveltyProtein composition differences between broken and unbroken rice grains have significant implications for human nutrition and in part explain differences in HRY. Rice breeders face the challenge of balancing the two competing traits of HRY and soft grain texture.

INFLUENCE OF HARVESTING METHODS ON YIELD AND QUALITY OF RICE IN THE REPUBLIC OF MACEDONIA

In this study, the influence of two different paddy harvesting methods (manual harvesting and combine harvesting) on paddy yield, head rice yield and white rice yield was investigated. Field trials were set up in three different locations in the rice producing regions Kocani, Cesinovo-Oblesevo and Stip under the standard production technology, adopted in the entire Macedonian rice production. Two Italian introduced varieties (San Andrea and Onice) were included in the trials. Samples were taken from the treatments with different methods of harvesting (manual and combine harvesting) from which the paddy rice yield data were collected directly. In order to determine the head rice yield, laboratory milling of paddy grains was performed on a paddy quality testing machine (three average samples of 100 g per treatment, duration of milling 1,40 min.). On the base of the data for paddy rice yield and head rice yield, the white rice yield was estimated. According to the results obtained, the highest paddy rice yield (11,925.67 kg ha-1) as well as the highest white rice yield (6,710.57 kg ha-1) were achieved in the treatment with manual harvesting in Kocani region (San Andrea variety). The highest head rice yield (65.80 %) was determined in the treatment with manual harvesting in Stip region (Onice variety), while the lowest head rice yield (43.90 %) was in the treatment with combine harvesting of the variety Onice in Kocani region. In general, the method of manual harvesting resulted in higher values of paddy yield, head rice yield and white rice yield compared to the method of mechanized, combine harvesting in all the examined treatments (two varieties, three locations).

The study of quality attributes of parboiled rice during steaming process with revolved sieve

The steaming process with revolved sieve was studied as a function of steaming time and revolution velocity. The quality of parboiled rice in terms of thermal property, head rice yield and color was investigated and compared to the conventional steaming process such as fixed sieve. The experimental results showed that the steaming process with revolved sieve had advantage over the steaming process with fixed sieve. It led to a steamed sample with higher DG higher head rice yield and lower whiteness value. The required steaming time for a regularity quality by a steaming process with revolved sieve was also shorter. Moreover, the steaming time affected the qualities of parboiled rice. The long steaming time provided the higher DG and head rice yield and lower whiteness value of parboiled rice. Considering revolution velocity, it was found that the revolution velocity did not affect the qualities of parboiled rice. However, the revolution velocity of 5 rpm with steaming time of 5 min provided the difference of quality at each layer.